23 research outputs found
Nuclear kinetic energy spectra of D_2^+ in intense laser field: Beyond Born Oppenheimer approximation
Simultaneously, the vibrational nuclear dynamics and full dimensional
electronic dynamics of the deuterium molecular ion exposed to the linear
polarized intense laser field are studied. The time dependent Schr\"odinger
equation of the aligned D2+ with the electric laser field is solved for the
simulation of the complicated dissociative ionization processes and compared
with the recent related experimental results. In this work, the R-dependent
ionization rate and the enhanced ionization phenomenon beyond the
Born-Oppenheimer approximation (BOA) are introduced and calculated. The
substructure of the nuclear kinetic energy release spectra are revealed as the
Coulomb explosion energy spectra and dissociation energy spectra in the
dissociation-ionization channel. The significant and trace of these distinct
sub-spectra in the total spectra comparatively are displayed and discussed.Comment: 17 pages, 4 figure
Detailed instantaneous ionization rate of H in intense laser field
Component instantaneous ionization rate (IIR) is introduced and the approach
of its calculation is formulated. The component IIR's and the overall
(time-averaged) component ionization rates are calculated for H at
different values of inter-nuclear distance in a linearly polarized laser field
with W cm intensity and nm
wavelength by direct numerical solution of the fixed-nuclei full dimensional
time-dependent Schr \"odinger equation. The exact overall component ionization
rates calculated by time-averaging of the component IIR are compared with those
calculated approximately via the virtual detector method (VD). Details of the
time dependent behavior of the outgoing and incoming electron wavepackets of
the H system in intense laser field at sub-femtosecond time scale are
studied based on the calculated component IIR. It is shown clearly that the
positive (outgoing electron wavepacket) signals of the IIR and its z component
are strong and sharp but the negative (returning electron wavepacket) signals
of the IIR are smooth and weak. The structure of the component of the
IIR has smooth structure. Relation between the R-dependent ionization rate and
duration of the ramp of the laser pulse is studied and it is explicitly shown
that for internuclear distance R<5.6, when the laser pulse is turned on without
a ramp, the first peak of R-dependent ionization rates moves towards the peak
of the lower time dependent Floquet quasi-energy state (QES).Comment: 28 pages, 7 figure
Nuclear classical dynamics of H in intense laser field
In the first part of this paper, the different distinguishable pathways and
regions of the single and sequential double ionization are determined and
discussed. It is shown that there are two distinguishable pathways for the
single ionization and four distinct pathways for the sequential double
ionization. It is also shown that there are two and three different regions of
space which are related to the single and double ionization respectively. In
the second part of the paper, the time dependent Schr\"{o}dinger and Newton
equations are solved simultaneously for the electrons and the nuclei of H
respectively. The electrons and nuclei dynamics are separated on the base of
the adiabatic approximation. The soft-core potential is used to model the
electrostatic interaction between the electrons and the nuclei. A variety of
wavelengths (390 nm, 532 nm and 780 nm) and intensities (
and ) of the ultrashort intense laser
pulses with a sinus second order envelope function are used. The behaviour of
the time dependent classical nuclear dynamics in the absence and present of the
laser field are investigated and compared. In the absence of the laser field,
there are three distinct sections for the nuclear dynamics on the electronic
ground state energy curve. The bond hardening phenomenon does not appear in
this classical nuclear dynamics simulation.Comment: 16 pages, 7 figure